From 5f842ee68a2a839e32d6dafaafcc1d4a26fcfc6a Mon Sep 17 00:00:00 2001 From: zhenggy Date: Tue, 14 Sep 2021 09:51:15 +0800 Subject: [PATCH] tcp: fix tp->undo_retrans accounting in tcp_sacktag_one() commit 4f884f3962767877d7aabbc1ec124d2c307a4257 upstream. Commit 10d3be569243 ("tcp-tso: do not split TSO packets at retransmit time") may directly retrans a multiple segments TSO/GSO packet without split, Since this commit, we can no longer assume that a retransmitted packet is a single segment. This patch fixes the tp->undo_retrans accounting in tcp_sacktag_one() that use the actual segments(pcount) of the retransmitted packet. Before that commit (10d3be569243), the assumption underlying the tp->undo_retrans-- seems correct. Fixes: 10d3be569243 ("tcp-tso: do not split TSO packets at retransmit time") Signed-off-by: zhenggy Reviewed-by: Eric Dumazet Acked-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index eb062fab6257..9382caeb721a 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1225,7 +1225,7 @@ static u8 tcp_sacktag_one(struct sock *sk, if (dup_sack && (sacked & TCPCB_RETRANS)) { if (tp->undo_marker && tp->undo_retrans > 0 && after(end_seq, tp->undo_marker)) - tp->undo_retrans--; + tp->undo_retrans = max_t(int, 0, tp->undo_retrans - pcount); if (sacked & TCPCB_SACKED_ACKED) state->reord = min(fack_count, state->reord); } -- 2.20.1